(1) Field of the Invention
The present invention relates to a conductimetric biosensor device with spaced apart electrodes as part of a test kit, wherein conductance or resistance is measured between electrodes. In particular, the present invention relates to the biosensor device which uses a fluid mobile ferromagnetic particles bound to a conductive polymer bound to (moiety of) a capture reagent (such as an antibody) as a composition which captures an analyte in a fluid sample. The complex then migrates to a capture zone where the complexed analyte is captured by another capture reagent (such as a monoclonal or polyclonal antibody) bound to (immobilized on) a substrate. The conductance or resistance between the electrodes are then measured. Bacteria are particularly detected by the biosensor device. Multiple detections can be accomplished simultaneously in different parallel arrays on the biosensor device with different capture reagents and complexes between different sets of electrodes.
(2) Description of Related Art
Assays based upon conductivity or resistance are well known. Illustrative patents are U.S. Pat. No. 5,312,762 to Guiseppi-Elie and U.S. Pat. No. 5,670,031 to Hintsche et al. Illustrative published art is Kim et al., Biosensor & Bioelectrics 14 907, 915 (published in February of 2000). In this art, conductive polymers are used as sensors of analytes ('762 patent and Kim et al) and microsized test devices (Hirtsche et al) are used to detect an analyte. In Kim et al, a conductive polymer is bonded to conductive gold particles, which also serve as a visually detectable reagent, for a conductimetric assay. In this assay, the analyte in a sample is added to the test device, bound by the gold labeled particles and then targeted to a site when there is a capture reagent between electrodes. The conductimetric test is then performed. One problem with the Kim et al assay is that the sample is applied to the test device and migrates along the test device to complex with the capture reagent. The sample can contain materials which reduce the efficiency of the assay.
Various types of immunoassays based upon detecting a signal from a capture reagent are described in U.S. Pat. No. 5,620,845 to Gould et al.; U.S. Pat. No. 4,486,530 to David et al.; U.S. Pat. No. 5,559,041 to Kang et al.; U.S. Pat. No. 5,656,448 to Kang et al.; U.S. Pat. No. 5,728,587 to Kang et al.; U.S. Pat. No. 5,695,928 to Stewart et al.; U.S. Pat. No. 5,169,789 to Bernstein et al.; U.S. Pat. Nos. 5,177,014, 5,219,725, and 5,627,026 to O'Conner et al.; U.S. Pat. No. 5,976,896 to Kumar et al.; U.S. Pat. Nos. 4,939,096 and 4,965,187 to Tonelli; U.S. Pat. No. 5,256,372 to Brooks et al.; U.S. Pat. Nos. 5,166,078 and 5,356,785 to McMahon et al.; U.S. Pat. Nos. 5,726,010, 5,726,013, and 5,750,333 to Clark; U.S. Pat. Nos. 5,518,892, 5,753,456, and 5,620,895 to Naqui et al.; U.S. Pat. Nos. 5,700,655 and 5,985,594 to Croteau et al.; and U.S. Pat. No. 4,786,589 to Rounds et al. The aforementioned U.S. patents are hereby incorporated herein by reference.